Circular polarized dichroic ratio

The circular polarized dichroic ratio D is represented in the following equation. 

Circular dichroism is usually measured as a dichroic ratio, which is the ratio of the optical densities of an absorption band in the direction of the polarized light (parallel over perpendicular) to a specified direction in the sample. More specifically, dichroic ratios depend on the angle 0, as shown in Figure 12.2b. The tangent of 0 is the ratio of the minor axis b to the major axis a of the ellipse that is defined as... 

CD is often given in terms of the eUipticity, 0. 6 is obtained ftom the ratio of the minor and major axes of the ellipse traced out by the electric field vector of the elliptically polarized light that emerges ftom a circularly dichroic sample onto which linearly polarized light was inddent. 

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